** EMGARGOED UNTILL 7AM JST SATURDAY, SEPT. 6, 2008 ** In this photo released by Imperial Household Agency, Japanese Prince Hisahito, the son of Prince Akishino and Princess Kiko, piles block at their residence in Tokyo Tuesday, Aug. 26, 2008. Prince Hisahito, Japanese imperial family’s first male heir to be born in 41 years, celebrated his second birthday on Saturday, Sept. 6, 2008. (AP Photo/Imperial Household Agency, HO) ** EDITORIAL USE ONLY**